Perhaps you should try some spelling variations:
hieu quang » thieu quang, hieu quan, hieu qua
thanh sann » thanh van, thanh anh, thanh son
dung tuong » dung thuong, dung truong, dung trong
hieu sang » chieu sang, hieu lang, nhieu tang
tuan dung » tuan duong, tran dung, tan dung
tuong dan » huong dan, tung dan, xuong dan
dan toan » van toan, dan than, manh toan
toan cau » toan cao, toan ban, toan tap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((hieu sang) OR (hieu quang)) - ((thanh sann) or (thanh san)) tuan dung tuong dan toan cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((hieu sang) OR (hieu quang)) - ((thanh sann) OR (thanh san)) tuan dung tuong dan toan cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((hieu sang) OR (hieu quang)) - ((thanh sann) or (thanh san)) tuan dung tuong dan toan cau*".